Rotary hook for sewing machines



Jan. 22, 1963 G. J. HABEDANK ETAL- 3,074,367

ROTARY Hoox FOR SEWING MACHINES INVENTORS. GusTAv J. HABEDANK AN LUDWIG J. KUHAR ATTRVEY J'an 22, 1963 s. J. HABEDANK Erm. 3,074,367

ROTARY Hoox FOR SEWING MACHINES 3 Sheets-Sheet 2 Filed May 6, 1960 INVENTORS GusTAv J. HABEDANK ma LuDw/G J. KUHAR BY E ITTORNEY WITNESS G. J. HABEDANK Erm. 3,074,367

ROTARY Hoox FOR SEWING MACHINES 3 Sheets-Sheet 3' Jan. .22, 1963 Filed May 6, 1960 INVENTORS GusTAv J, HABEDANK .ma LuDw/c,` J. KUHAR tied The present invention relates to a rotary hook for a sewing machine.

The object of this invention is to provide a sewing machine rotary hook that is specifically adapted to sew very heavy thread, but which at the same time, is capable of sewing with normal threads, `or in other words, to increase the versatility of a conventional rotary hook by making it capable of sewing a wider range of threads. It is a further obiect of this inventionI to improve the thread handling characteristics of a conventional rotary hook to facilitate passage of the limb of needle thread across the face ot the hook. lt is a further object of this invention to reduce the manufacturing expense of a conventional rotary hook.

Having in mind the above and other objects that will be evident from an understanding of this disclosure, the invention comprises the devices, combinations and arrangements oi parts as illustrated in the presently preferred embodiment or" the invention which is hereinafter set forth in such detail as 4to enable those skilled in the art readily to understand the function, operation, construction and advantages of it when' read in conjunction with the accompanying drawings in which:

FIG. l is a fragmentary vertical sectional view, taken transversely of the bed of a sewing machine, illustrating in elevation a rotary hook in accordance with this invention.

FEiG. 2 is a perspective view of the bobbin case carrier per se of the rotary hook o lilG. l.

FlG. 3 is a fragmentary top plan View of the bobbin case carrier and the rotation restraining means of the sewing machine of PEG. l, with the hook body illustrated in section.

FIG. 4 is a view similar to FlG. l, but showing the parts in' a diiierent position.

PEG. 5 is a horizontal sectional view of the rotary hoolt in accordance with this invention and taken substantially on the line -S of FIG. A..

FlG. 6 is a vertical sectional view taken substantially on the line 6-6 of FlG. 5.

FGS. 7, 8, 9 and l0 are perspective views of a rota-ry hooi; in accordance with this invention, illustrating in successive steps the path assumed by the needle thread as it is being withdrawn from the hook.

With reference to the drawings there is illustrated fragmentary portions of the bed l of a sewing machine having a throat plate 2. upon which work W is supported and is held down by a presser foot 3. The throat plate 2 has a needle aperture d through which an endwlse movable needle Ei, FGS. 7-lG, is adapted to pass and to cooperate in the formation of lock stitches with a looptaker (i, or more particularly a horizontal axis rotary hook of the type that makes two complete revolutions for each reciprocatiou of the needle S.

The hook 6, which is the subject of this invention7 cornpises a cup-shaped hook body '7 having a bore ii for receiving the end of a hook shaft 9 journaled in the bed The hool; body 7 is formed with a loop seizing beak 'lll and with an internal circular raceway 11 in which is journaled a discontinuous bearing rib l2 on the periphery of a bobbin case carrier i3. The raceway il has an open side that is closed by a gib ifi on which is formed a loop controlling tail l5. Secured to the periphery of the hook body 7 is a thread guard i6 having a leading E Zilddl Patented clan. 22, i953 end 17 overhanging the beak lll and a thread engaging edge l@ that serves to elle-ct pull-oli of the bobbin thread and to lift the one limb of the needle thread onto the face of the hook. The trailing end of the thread guard i6 is formed with a needle clearance notch i9.

The bobbin case carrier lli is tformed with a cylindrical side wall 2li upon the periphery of which is the bearing rib t2. The bearing rib has a gap therein dening a loop detainin'g shoulder 2li at one end and a loop controlling shoulder 22 at the other end. The bottom of the bobbin case carrier l is closed by a diameter bar 213 that carries the bobbin case receiving post 2d. On the top of the side wall 7d there is a loop controlling dance Z5. The side wall of the bobbin case carrier is provided at the top thereof with a needle clearance aperture 2d. The needle 5 descends at approximately the center or" the aperture 26 and delin'es the loop seizing position of the hook, i.e., the position at which the beak it? initially enters the loop of thread thrown by the needle. The loop seizing position divides the bobbin case carrier i3 diametrically into a cast-on side and a cast-od' side.

The lange 25 extends on the cast-od side of the bobbin case carrier from a point substantially opposite from the loop seizing position to the lop seizing position, and continues for approximately sixty degrees, as indicated by the arc X in FIG. l, beyond the loop seizing position on the cast-on side. Adiacen-t to the loop seizing position, the flange 25 is provided with a notch 27 that receives a lug 23 of a rotation restraining linger 29.

The bobbin case `carrier i3 receives a bobbin case 3d in which is mounted bobbin 3l and which is held in the bobbin case carrier by a latch including a slide 32 that cooperates with a groove 33 in the free end of the post 24. On the periphery of the bobbin case 3d there is mounted a bobbin thread tension spring 3d from beneath which emerges the lead of bobbin thread B from the bobbin Si. The lead of bobbin :thread is directed toward the point of stitch formation by a slot 3dr: in the cast-on side of the flange 2S adjacent to the rotation restraining notch 27.

The construction as above described is conventional and is discolsed for example in the United States patents of Kessler, Nos. 1,995,278 and 2,685,699. The hook is adapted to operate in the usual manner. 0n the downward stroke, the needle 5 which carries the needle thread T penetrates the work W and passes closely adjacent to the path of travel of the beak itl. On the upward stroke, the needle throws a loop of the needle thread 'l into the path of travel of the beak lil which enters the loop and casts it about Ithe bobbin case carrier l to concatenate it with the bobbin thread B to form a lock stitch.

With reference to FlG. 6, it will be seen that the bobbin case carrier 13 is mounted eccentrically in the hook body 7. The raceway il. in the hook body 7 is concentric relatively to the axis of rotation of the hook, which is the axis of the hook shaft 9. The side wall 2li of the bobbin case carrier 13 is cylindrical about an axis A that coincides with the axis of the post 24 and defines the axis of the bobbin case carrier. The eccentricity is obtained by making the bearing rib l2 eccentric relatively to the axis A. The axis of the bearing rib is shown at C and is offset relatively to the axis A in a direction on a radial line falling between the shoulders 2l and 22 so that the periphery of the bearing rib l2 at a point between shoulders 2l and 22 is further from the axis A than is the diametrically opposite point. The net eliect of this construction is to position the bobbin case carrier i3 lower in the hook body 7, thus increasing the distance between the outer surface of the side wall Ztl of the bobbin case carrier 13 and the inner wall 35 of the hook body 7 in the area between the shoulders 21 and 22. The needle limb designated TN of the needle thread T that passes behind the bobbin case carrier 13, passes through this gap, that is, it comes from the needle 5, through the aperture 4 in the throat plate 2, and then across the top of the side Wall 20 of the bobbin case carrier 13 in front of the loop detaining shoulder 21 which has stripped it from the under surface of the beak 10, behind the bearing rib 12 to the throat 36 at the base of the beak 1h. Thus, increasing the depth of the gap provides for accommodation of a heavier thread.

Since heavy threads require larger needles, it is necessary to increase the size of the needle clearance aperture 26 relatively to constructions now in use. Since the relation of the needle relatively to the path of the beak lll cannot be altered, the increased size of the needle aperture 26 has been accommodated by moving the ange 25 axially the required amount, or in other words, the side wall of the bobbin case carrier 15 has been made wider in comparison to the conventional constructions.

In addition to the needle limb TN, which passes behind the bobbin case carrier 13, the needle thread T also includes a work limb TW which passes across the face of the bobbin case carrier 13. The limb TW is anchored in the work by the previous stitch and extends through the aperture 4 in the throat plate 2 to the throat 36 in the hook body. While the limb TW is initially disposed at the rear of the beak lil, that is at loop seizure it is on the edge 37 of the beak 1t) away from the needle S, it is shifted forwardly by the thread engaging: edge 18 of the thread guard 16 and eventually passes across the front face of the bobbin case carrier 13 and bobbin case 30.

With reference to FIG. l, after loop seizure the loop of the needle thread T is expanded by the advance of the hook 6 and the Work limb TW is in effect laid upon the periphery of the bobbin case carrier 13 or, more particularly, is laid upon the top or free edge 38 of the short section of the ange 25 on the cast-on side of the bobbin case carrier. As heretofore constructed, the free edge 33 has been made at and the thread limb TW would lay on the same until forced off by the thread engaging edge 18 of the thread guard 16. Since the advance of the edge 18 must be smooth and must be delayed to provide for clearance of the needle, the limb TW is normally disposed upon the edge 3S for an appreciable period of time and tends to Wrap or bend around the same. This action consumes a certain amount of thread and hinders the free and smooth passage of the thread limb around the bobbin case carrier 13 as is necessary in modern high speed sewing machines.

` In accordance with the present invention, the above defect has been overcome by providing a bevel or inclined surface 39 on the front of the edge 33. Thus, the thread limb TW is laid on the inclined surface 39 rather than on the flat edge 38 and will immediately slide off and begin to pass across the front face of the hook. At the same time, the short section of the flange 25 on the cast-on side is provided Witha notch 4t) immediately past the rotation restraining notch 27 which in eiect reduces the height of the ilange 25 at this point to facilitate passage of the thread limb TW over the ange 25, thereby further facilitating cast-on.

A further advantage of the present construction is that it simplifies and thereby reduces the manufacturing cost of the hook. As heretofore constructed, the short section of the flange 25 on the cast-on side was machined in two successive operations, one for the front face thereof and one for the edge 38. This produced a sharp edge between the two surfaces that Was removed in the subsequent hand tiling operation. By means of the inclined surface 39, the necessity for the rather costly hand tiling operation has been eliminated.

Also to facilitate passage of the thread limb TW across the f ace. of. the hook, the end of the flangel 25 that receives the thread limb TW after cast-on has been provided with an inclined surface 41 which, as seen in FIG. 4, facilitates passage of thetthread limb onto the flange and prevents it from being caught against the edge and thereby detained. Y

The fiange 25 has also been provided with a notch 42 on the cast-oft side thereof immediately adjacent to the rotation restraining notch 27. The notch 42 includes a rst edge 43 and a second edge 44 which converge to a throat 45. Speciiically, the edge 43 begins at a point as indicated by the angle Y in FIG. l, approximately forty degrees in front of the loop seizing position, which is the point at which the beak 10 initially enters the loop of the needle thread T. It is at this point in the cycle that the take-up mechanism has substantially Withdrawn the slack thread in the system that was produced by cast-off of the loop by the hook. The edge 43 extends on substantially a straight line toward the innermost portion of the rotation restraining notch 27, that is below the lug 2S from beneath which the work limb TW emerges, FIG. 7, to produce a shorter path for the thread T. The edge 44 extends on substantially a straight line from the throat 45 toward a point just above the loop seizing position and below the point of stitch formation toward which the loop is being drawn. The edge 44 serves to provide a smooth passage for the thread loop as it is being Withdrawn. Y

More particularly, the function of the notch 42 is to provide a smoother and straighter path for the needle thread T as it is being Withdrawn from the hook. Heavy threads are relatively inexible and thus do not readily bend sharply about corners. Reference is made to FIGS. 7-10 which show in four successive steps the hook in the final portion of the stitching cycle as the needle thread T is Withdrawn from the hook. At this point, the needle thread has been drawn off the beak 10 onto the loop controlling tail 15. The needle limb TN has moved from the shoulder 21 to the shoulder 22 and extends behind the bearing rib 12 to the tail 15. The work limb TW is in the notch 27 behind the lug 28 of the rotation restraining inger and extends to the tail 15. The needle thread T is being withdrawn at this time in the cycle at a very rapid rate. If at any time, the thread should become snubbed, there would be thread stealing and resulting looping as the stitch is set.

At the point illustrated in FIG. 7, the take-up action on the thread has Withdrawn substantially all of the slack thread that resulted from movement of the loop from the throat 36 onto the tail 15. Thereafter, the inability of the heavy thread to bend sharply about the tail l5 and to pass readily under the lug 27, consumes a certain amount of thread. This causes a snubbing action that will tension the thread to the point where thread stealing from its supply Will occur. It is at this point that the notch 42 becomes effective to reduce the length of the thread path and to provide a smooth path which the heavy threads can follow. T he thread limb slides into the notch 42 and smoothly out along the edge 44 with the only drag on the thread being that which is a necessary result of the thread moving under the lug 28 of the rotation restraining notch. The condition that exists With heavy thread is aggravated by the fact that the flange 25 must be moved outwardly to provide for increasing the size of needle aperture 26 as noted above. Thus, the length of the thread path is inherently increased for sewing With heavy threads. It has been found that the notch 42 not only permits successful operation of the hook with heavy threads but also improves the thread handling with normal threads. This feature thus contributes to making a universal hook that is adapted to sew with a wide range of threads.

A further advantage of the hook in accordance with this invention is that the tendency to build up lint is materially reduced. The oil provided for lubrication of the hookv raceway causes the lint to adhere to and build up on the surface of the bobbin case carrier 13, particularly about the needle aperture 26 Where it prevents proper loop formation. The enlargement of the needle aperture 26, coupled with the notches 40 and 42 reduces the area behind the -ilange 25 upon which lint can accumulate.

Numerous alterations of the structure herein disclosed will suggest themselves to those skilled in the art. However it is to be understood that the present disclosure relates to a preferred embodiment of our invention which is for purposes of illustration only and not to be construed Ias a limitation of the' invention. All such modifications which do not depart from the spirit of the invention are intended to be included within the scope of the appended claims.

Having thus set forth the nature of the invention, what We claim herein is:

l. A horizontal axis rotary hook comprising a cupshaped hook body having an internal circular raceway and a loop seizing beak, a stationary bobbin case carrier having a cylindrical side wall deiining la bobbin receiving cavity and a discontinuous circular bearing rib on said side Wall and journaled in said raceway for rotation of said hook body relatively to said bobbin case carrier, said beak having a loop seizing position relative to said bobbin case carrier and dividing said bobbin case carrier diametrically into a cast-on side and a cast-01T side, a laterally extending loop controlling flange on the top of said side wall on the cast-off side of said bobbin case carrier and terminating in a free edge disposed closely adjacent to the path of travel of said beak, said ange having a rotation restraining notch formed in the face thereof at said loop seizing position for receiving -a rotation restraining nger and having a thread loop clearance notch formed in the free edge thereof and defining a smooth continuation of said free edge, said thread loop clearance notch including a rst edge beginning at a point approximately forty degrees from said loop seizing position on the cast-olf side and extending on substantially a straight line toward the innermost portion of said rotation -restraining notch and terminating in a throat, and a second edge extending from said throat on substantially a straight line toward a point immediately adjacent to sai-d loop seizing position.

2. A horizontal `axis rotary hook comprising -a cupshaped hook body having an internal circular raceway and a loop seizing beak, a stationary bobbin case carrier having a cylindrical side wall defining a bobbin receiving cavity and a discontinuous circular bearing rib on said Iside Wall and journaled in said raceway for rotation of said hook body relatively to said bobbin case carrier, said beak having a loop seizing position relative to said bobbin case carrier and dividing said bobbin case carrier diametrically into a cast-0n Side and a cast-off side, a laterally extending loop controlling flange on the top of said side wall on said cast-oit side and extending for approximately sixty degrees beyond said loop seizing position on said cast-on side, said flange terminating in a free edge disposed closely adjacent to the path of travel of said beak on said cast-off side and decreasing in radius on said cast-on side, said flange having a rotation restraining notch formed in the face thereof at said loop seizing position for receiving a rotation restraining finger and having a bobbin thread guiding slot in the face thereof on the cast-on side of and adjacent to said rotation restraining notch, said free edge of said flange on said cast-on side having a surface inclined in a direction inwardly radially and axially toward the face of said flange for directing a limb of the needle thread loop onto the face of said lbobbin case carrier.

References Cited in the file of this patent UNITED STATES PATENTS 1,995,278 Kessler Mar. 19, 1935 2,435,358 Kessler Feb. 3, 1948 2,694,373 Covert et al Nov. 16, 1954 2,839,019 Heimann .Tune 17, 1958 

1. A HORIZONTAL AXIS ROTARY HOOK COMPRISING A CUPSHAPED HOOK BODY HAVING AN INTERNAL CIRCULAR RACEWAY AND A LOOP SEIZING BEAK, A STATIONARY BOBBIN CASE CARRIER HAVING A CYLINDRICAL SIDE WALL DEFINING A BOBBIN RECEIVING CAVITY AND A DISCONTINUOUS CIRCULAR BEARING RIB ON SAID SIDE WALL AND JOURNALED IN SAID RACEWAY FOR ROTATION OF SAID HOOK BODY RELATIVELY TO SAID BOBBIN CASE CARRIER, SAID BEAK HAVING A LOOP SEIZING POSITION RELATIVE TO SAID BOBBIN CASE CARRIER AND DIVIDING SAID BOBBIN CASE CARRIER DIAMETRICALLY INTO A CAST-ON SIDE AND A CAST-OFF SIDE, A LATERALLY EXTENDING LOOP CONTROLLING FLANGE ON THE TOP OF SAID SIDE WALL ON THE CAST-OFF SIDE OF SAID BOBBIN CASE CARRIER AND TERMINATING IN A FREE EDGE DISPOSED CLOSELY ADJACENT TO THE PATH OF TRAVEL OF SAID BEAK, SAID FLANGE HAVING A ROTATION RESTRAINING NOTCH FORMED IN THE FACE THEREOF AT SAID LOOP SEIZING POSITION FOR RECEIVING A ROTATION RESTRAINING FINGER AND HAVING A THREAD LOOP CLEARANCE NOTCH FORMED IN THE FREE EDGE THEREOF AND DEFINING A SMOOTH CONTINUATION OF SAID FREE EDGE, SAID THREAD LOOP CLEARANCE NOTCH INCLUDING A FIRST EDGE BEGINNING AT A POINT APPROXIMATELY FORTY DEGREES FROM SAID LOOP SEIZING POSITION ON THE CAST-OFF SIDE AND EXTENDING ON SUBSTANTIALLY A STRAIGHT LINE TOWARD THE INNERMOST PORTION OF SAID ROTATION RESTRAINING NOTCH AND TERMINATING IN A THROAT, AND A SECOND EDGE EXTENDING FROM SAID THROAT ON SUBSTANTIALLY A STRAIGHT LINE TOWARD A POINT IMMEDIATELY ADJACENT TO SAID LOOP SEIZING POSITION. 